Oleuropein or rutin consumption decreases the spontaneous development of osteoarthritis in the Hartley guinea pig

Role of l-arginine/nitric oxide/cyclic GMP/KATP channel signaling pathway and opioid receptors in the antinociceptive effect of rutin in mice

The l-arginine (l-Arg)/nitric oxide/cyclic GMP/potassium channel (KATP) pathway and opioid receptors are known to play critical roles in pain perception and the antinociceptive effects of various compounds. While there is evidence suggesting that the analgesic effects of rutin may involve nitric oxide modulation, the direct link between rutin and the l-Arg/nitric oxide/cyclic GMP/KATP pathway in the context of pain modulation requires further investigation. The antinociceptive effect of rutin was studied in male NMRI mice using the formalin test. To investigate the role of the l-Arg/nitric oxide/cyclic GMP/KATP pathway and opioid receptors, the mice were pretreated intraperitoneally with different substances. These substances included l-Arg (a precursor of nitric oxide), S-nitroso-N-acetylpenicillamine (SNAP, a nitric oxide donor), N(gamma)-nitro-l-arginine methyl ester (L-NAME, an inhibitor of nitric oxide synthase), sildenafil (an inhibitor of phosphodiesterase enzyme), glibenclamide (a KATP channel blocker), and naloxone (an opioid receptor antagonist). All pretreatments were administered 20 min before the administration of the most effective dose of rutin. Based on our investigation, it was found that rutin exhibited a dose-dependent antinociceptive effect. The administration of SNAP enhanced the analgesic effects of rutin during both the initial and secondary phases. Moreover, L-NAME, naloxone, and glibenclamide reduced the analgesic effects of rutin in both the primary and secondary phases. In conclusion, rutin holds significant value as a flavonoid with analgesic properties, and its analgesic effect is directly mediated through the nitric oxide/cyclic GMP/KATP channel pathway.

NOTCH1: A Novel Player in the Molecular Crosstalk Underlying Articular Chondrocyte Protection by Oleuropein and Hydroxytyrosol

Osteoarthritis (OA) is the most common joint disease, but no effective and safe disease-modifying treatment is available. Risk factors such as age, sex, genetics, injuries and obesity can concur to the onset of the disease, variably triggering the loss of maturational arrest of chondrocytes further sustained by oxidative stress, inflammation and catabolism. Different types of nutraceuticals have been studied for their anti-oxidative and anti-inflammatory properties. Olive-derived polyphenols draw particular interest due to their ability to dampen the activation of pivotal signaling pathways in OA. Our study aims to investigate the effects of oleuropein (OE) and hydroxytyrosol (HT) in in vitro OA models and elucidate their possible effects on NOTCH1, a novel therapeutic target for OA. Chondrocytes were cultured and exposed to lipopolysaccharide (LPS). Detailed analysis was carried out about the OE/HT mitigating effects on the release of ROS (DCHF-DA), the increased gene expression of catabolic and inflammatory markers (real time RT-PCR), the release of MMP-13 (ELISA and Western blot) and the activation of underlying signaling pathways (Western blot). Our findings show that HT/OE efficiently attenuates LPS-induced effects by firstly reducing the activation of JNK and of the NOTCH1 pathway downstream. In conclusion, our study provides molecular bases supporting the dietary supplementation of olive-derived polyphenols to revert/delay the progression of OA.

Natural Compounds: Potential Therapeutics for the Inhibition of Cartilage Matrix Degradation in Osteoarthritis

Osteoarthritis (OA) is the most common degenerative joint disease characterized by enzymatic degradation of the cartilage extracellular matrix (ECM) causing joint pain and disability. There is no disease-modifying drug available for the treatment of OA. An ideal drug is expected to stop cartilage ECM degradation and restore the degenerated ECM. The ECM primarily contains type II collagen and aggrecan but also has minor quantities of other collagen fibers and proteoglycans. In OA joints, the components of the cartilage ECM are degraded by matrix-degrading proteases and hydrolases which are produced by chondrocytes and synoviocytes. Matrix metalloproteinase-13 (MMP-13) and a disintegrin and metalloproteinase with thrombospondin motifs 4 and 5 (ADAMTS5) are the major collagenase and aggrecanase, respectively, which are highly expressed in OA cartilage and promote cartilage ECM degradation. Current studies using various in vitro and in vivo approaches show that natural compounds inhibit the expression and activity of MMP-13, ADAMTS4, and ADAMTS5 and increase the expression of ECM components. In this review, we have summarized recent advancements in OA research with a focus on natural compounds as potential therapeutics for the treatment of OA with emphasis on the prevention of cartilage ECM degradation and improvement of joint health.

Naturally Occurring Osteoarthritis Features and Treatments: Systematic Review on the Aged Guinea Pig Model

To date, several in vivo models have been used to reproduce the onset and monitor the progression of osteoarthritis (OA), and guinea pigs represent a standard model for studying naturally occurring, age-related OA. This systematic review aims to characterize the guinea pig for its employment in in vivo, naturally occurring OA studies and for the evaluation of specific disease-modifying agents. The search was performed in PubMed, Scopus, and Web of Knowledge in the last 10 years. Of the 233 records screened, 49 studies were included. Results showed that within a relatively short period of time, this model develops specific OA aspects, including cartilage degeneration, marginal osteophytes formation, and subchondral bone alterations. Disease severity increases with age, beginning at 3 months with mild OA and reaching moderate–severe OA at 18 months. Among the different strains, Dunkin Hartley develops OA at a relatively early age. Thus, disease-modifying agents have mainly been evaluated for this strain. As summarized herein, spontaneous development of OA in guinea pigs represents an excellent model for studying disease pathogenesis and for evaluating therapeutic interventions. In an ongoing effort at standardization, a detailed characterization of specific OA models is necessary, even considering the main purpose of these models, i.e., translatability to human OA.

Rutin Inhibits the Progression of Osteoarthritis Through CBS-Mediated RhoA/ROCK Signaling

Osteoarthritis (OA) is a chronic joint disease characterized by the deterioration of cartilage and subchondral bone in the joints. Currently, there is no complete cure for OA, only treatments designed to temporarily relieve pain and improve function. Compared with the high cost of surgical treatment, medical treatment of OA is more acceptable and cost-effective. Rutin, as a flavonoid, has been shown to have anti-OA properties. We evaluated the effects of rutin on chondrocytes in lipopolysaccharide (LPS)-induced OA and on OA in rats induced by anterior cruciate ligament transection. We found that rutin effectively reduced the expression levels of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), tumor necrosis factor-α (TNF-α), and matrix metalloproteinase 13 (MMP-13) and increased the expression of Col II and aggrecan (p < 0.001). In addition, we also found that rutin increased the expression of cystathionine-β-synthase (CBS) and inhibited the expression of Rho-related coiled-coil protein kinase (ROCK) in chondrocytes (p < 0.05), thereby effectively inhibiting the inflammatory progression of OA. We concluded that rutin inhibits the inflammatory progression of OA through the CBS-mediated RhoA/ROCK signaling pathway.

Anti-Inflammatory Effects Induced by a Polyphenolic Granular Complex from Olive (Olea europaea, Mainly Cultivar coratina): Results from In Vivo and Ex Vivo Studies in a Model of Inflammation and MIA-Induced Osteoarthritis

MOMAST^® GR25 is a polyphenolic granular complex from olive pressing juice with high total content in polyphenols. In this work, we evaluated the possible anti-inflammatory effects of MOMAST^® GR25 in both acute and chronic inflammatory models. MOMAST^® GR25 decreased the levels of prostaglandin (PG) E₂ and 8-iso-PGF_2α in isolated rat colon, liver, and heart specimens stimulated with lipopolysaccharide (LPS). In vivo, compared to controls, rats treated with MOMAST^® GR25 (100 mg/kg to 1 g/kg) showed a significant reduction in both licking/biting time in the formalin test. In a rat model of osteoarthritis by monoiodoacetate (MIA) injection, MOMAST^® GR25 showed pain-relieving properties when acutely administered, reducing mechanical hyperalgesia and spontaneous pain. Moreover, a repeated daily treatment with MOMAST^® GR25 (300 mg/kg) fully counteracted osteoarticular pain without the development of tolerance to the antinociceptive effect. Taken together, our present findings showed that MOMAST^® GR25 could represent a potential strategy for the treatment of inflammation and pain.

In vivo methodologies to assist preclinical development of topical fixed-dose combinations for pain management

The combination in a fixed dose of two or more active pharmaceutical ingredients in the same pharmaceutical dosage form is an approach that has been used successfully in the treatment of several pathologies, including pain. In the preclinical development of a topical fixed-dose combination product with analgesic and anti-inflammatory activities for pain management, the main objective is to establish the nature of the interaction between the different active pharmaceutical ingredients while obtaining data on the medicinal product safety and efficacy. Despite the improvement of in vitro assays, animal models remain a fundamental strategy to characterise the interaction, efficacy and safety of active pharmaceutical ingredients at the physiological level, which cannot be reached by in vitro assays. Thus, the main goal of this review is to systematise the available animal models to evaluate the efficacy and safety of a new fixed-dose combination product for topical administration indicated for pain management. Particular emphasis is given to animal models that are accepted for regulatory purposes.

An oleuropein-based dietary supplement may improve joint functional capacity in older people with high knee joint pain: findings from a multicentre-RCT and post hoc analysis

Objectives:

To investigate a 6-month intervention with an olive leaf extract (OLE) on knee functionality and biomarkers of bone/cartilage metabolism and inflammation.

Design:

This randomized, double-blind, placebo-controlled, multi-centric trial included 124 subjects with knee pain or mobility issues. Subjects received twice a day one capsule of placebo or 125 mg OLE (Bonolive™, an OLE containing 50 mg of oleuropein) for 6 months. The co-primary endpoints were Knee injury and Osteoarthritis Outcome Score (KOOS) and serum Coll2-1NO2. The secondary endpoints were the subscales of the KOOS, knee pain VAS at rest and at walking, OARSI core set of performance-based tests and multiple inflammatory and bone or cartilage remodeling serum biomarkers and concentration of oleuropein’s metabolites in urine.

Results:

At 6 months, OLE group was not efficient on global KOOS score, changes of inflammatory and cartilage remodeling biomarkers compared to placebo. Post hoc analyses demonstrated a large and significant treatment effect of OLE in a sub-group of subjects with high walking pain at baseline ( p = 0.03). This was observed at 6 months for the global KOOS score, and each different subscale and for pain at walking ( p = 0.02). OLE treatment was well tolerated.

Conclusion:

OLE was not effective on joint discomfort excepted in a sub-group of subjects with high pain at treatment initiation. As oleuropein is well tolerated, OLE can be used to relieve knee joint pain and enhance mobility in subjects with articular pain.

Dose-dependent effects of oleuropein administration on regulatory T-cells in patients with rheumatoid arthritis: An in vitro approach

Introduction:

Rheumatoid arthritis (RA) is an autoimmune disease that is identified with chronic inflammation and progressive destruction of the joints. The defective activity of regulatory T cells (Tregs) plays a crucial role in RA development. Oleuropein (OLEU) is the most common polyphenolic compound in olive leaf extracts with numerous pharmacological activities. In this study, the potential effects of OLEU in shifting CD4⁺ T cells toward Tregs are evaluated in patients with RA.

Methods

32 healthy controls (HC) and 45 RA patients were included in two groups. The immunoturbidometric technique was used to measure serum levels of c-reactive protein (CRP) and rheumatoid factor (RF). Isolated CD4⁺ T cells from peripheral blood mononuclear cells (PBMCs) of HC and RA patients were cultured with appropriate concentrations of OLEU. The cytotoxicity effects of OLEU were determined using the MTT assay at 24, 48, and 72 h. The percentage of CD4⁺CD25 + FoxP3 regulatory T lymphocytes (Tregs) and the expressions of IL-10 and TGF-β were evaluated by flow cytometry and immunoassay techniques after treatment of cells with different concentrations of OLEU for 24 h. The serum levels of RF and CRP in patients with RA were 11.8 ± 5.32 IU/ml and 6.36 ± 5.82 mg/l, respectively.

Results

OLEU had a dose-dependent effect on the CD4⁺ T cells via increasing the frequency of CD4⁺CD25 + FoxP3 Tregs (p = 0.0001). Moreover, it induced the production of IL-10 (p = 0.0001) and TGF-β (p < 0.01) in both HC and RA patients.

Conclusion

The findings of this study suggest that OLEU may have immunomodulatory effects by inducing Tregs, and it might help in developing a novel nutrition strategy for management of autoimmune diseases such as RA.

Ingredients of a Natural Oral Nutritional Supplement and Their Role in the Treatment of Osteoarthritis

Osteoarthritis is a prevalent degenerative disease affecting a large portion of the world’s aging population. Currently, nonsteroidal anti-inflammatory drugs and acetaminophen are first-line medications for treating osteoarthritis patients’ pain. However, several studies have noted that while these medications control pain they do not halt progressive degeneration and tend to have an unfavorable side-effect profile with prolonged use. Recently, due to their more favorable side-effect profiles, herbal alternatives for controlling osteoarthritis symptoms and for alleviating the progression of the disease are being increasingly studied. Synogesic is a newly developed herbal supplement blend by renowned orthopedic surgeons and physiatrists consisting of turmeric, rutin, ginger root, vitamin C, vitamin D, and boswellia extracts. A study by Sharkey et al. has commented on the efficacy of the blend on the patients with knee osteoarthritis. So far, a review on the ingredients of the blend has not yet carried outbeen. By exploring prominent literature databases including PubMed and ScienceDirect, our aim is to write a narrative review to explore the individual ingredients of this blend and delve into their characteristics, as well as the most recent literature on their mechanism and efficacy in patients with osteoarthritis. Through this, we hope to inform clinicians and patients alike on relevant up-to-date research on the supplement and provide insight on the potential for this supplement for alleviating the disease course of patients with osteoarthritis.

Loss of Autophagy Causes Increased Apoptosis of Tibial Plateau Chondrocytes in Guinea Pigs with Spontaneous Osteoarthritis

OBJECTIVE

The goal of the present study was to observe the effect of autophagy in tibial plateau chondrocytes on apoptosis in spontaneous knee osteoarthritis (OA) in guinea pigs.

DESIGN

Fifty 2-month-old female Hartley guinea pigs were divided into a normal group (10 animals, all euthanized after 7 months) and an OA group (40 animals, 10 of which were euthanized after 10 months). Immunohistochemistry, RT-qPCR and Western blotting were used to evaluate autophagy levels, intracellular glycogen accumulation and apoptosis in tibial plateau chondrocytes in vivo and in vitro. The remaining 30 guinea pigs in the OA group were divided into 3 groups: a rapamycin group, a normal saline group, and a 3-methyladenine (3-MA) group. Intracellular glycogen accumulation and chondrocyte apoptosis were assessed by altering the level of autophagy in chondrocytes in vivo.

RESULTS

When spontaneous OA occurred in guinea pigs, autophagy levels in tibial plateau chondrocytes decreased, while intracellular glycogen accumulation and the rate of chondrocyte apoptosis increased. After enhancing the level of autophagy in tibial plateau chondrocytes in guinea pigs with OA, intracellular glycogen accumulation and the rate of chondrocyte apoptosis decreased, while inhibiting autophagy had the opposite effects.

CONCLUSION

The results indicate that the function of autophagy in chondrocytes may at least partly involve the catabolism of glycogen. In guinea pigs with OA, the level of autophagy in tibial plateau chondrocytes decreased, and chondrocytes were unable to degrade intracellular glycogen into glucose, leading to less energy for chondrocytes and increased apoptosis.

Protective Actions of Oral Administration of Bifidobacterium longum CBi0703 in Spontaneous Osteoarthritis in Dunkin Hartley Guinea Pig Model

OBJECTIVE

The aim of this study was to evaluate the effects of a lyophilized inactivated culture (LIC) from Bifidobacterium longum CBi0703 in a spontaneous model of osteoarthritis (OA) in Dunkin Hartley guinea pigs. Histology of cartilage and synovial membrane was the primary outcome. Biomarkers were also considered to evaluate the treatment efficacy.

DESIGN

LIC (1 µg/kg) with or without vitamin C (1 mg/kg) were tested in Dunkin Hartley guinea pigs spontaneously developing OA and compared with control (sterile water; CTL). Treatment was initiated orally in 16-week-old animals over a period of 12 weeks. Histological lesions of articular cartilage and synovial membrane were scored according to the OARSI (Osteoarthritis Research Society International) recommendations. Four biomarkers (Coll2-1, PIINAP, Fib3-2, and osteocalcin) were measured in animal sera.

RESULTS

The global OARSI score increased with time in all group but no significant difference between groups was observed. When score items were analyzed individually, a significant lower score of cartilage structure was observed in the LIC + vitamin C group compared with CTL (P < 0.0001). Synovial membrane showed a mild inflammatory reaction that was not affected by the treatment. LIC significantly decreased serum levels of Coll2-1 (P = 0.0004 vs. CTL), a marker of type II collagen degradation and LIC + vitamin C significantly increased PIINAP (P = 0.0003), a marker of type II collagen synthesis. The ratio Coll2-1/PIINAP was significantly decreased in both LIC groups (P < 0.001).

CONCLUSION

Lyophilized inactivated culture of B. longum CBi0703 administrated orally over a period of 12 weeks decreased cartilage structure lesions and decreased type II collagen degradation suggesting a potential prophylactic effect on OA development.

New Insights into the Antioxidant Compounds of Achenes and Sprouted Buckwheat Cultivated in the Republic of Moldova

It is well known that both Fagopyrum esculentum species, buckwheat achenes and buckwheat germs, contain flavonoids, and that they can be considered functional foods. In the present study we have analyzed the total content of polyphenols (TPC) and flavonoids (TFC), as well as the antioxidant activity of buckwheat ahcenes originating from the Balti region, Republic of Moldova, and also of the buckwheat sprouts over seven days of germination. The content of phytochemicals in achenes and germinated buckwheat after three and seven days was determined by HPLC–MS analysis. Using the Folin–Ciocalteu method, we recorded an increase in TPC of 360%, and of 436% in TFC after seven days of buckwheat ahcene germination. We aimed to investigate the free radical scavenging properties of methanolic extracts from ahcenes and sprouted buckwheat. We identified and quantified flavonoids and lignans such as rutin, orientin, isoorientin, vitexin, quercetin, quercitrin, isorhamnetin, lutein, apigenin, catechins, coumestrol—which have countless beneficial effects on human health—using HPLC–MS. FTIR analysis also revealed the accumulation of phenolic compounds during germination. This is the first study on the identification and quantification of phytochemicals from buckwheat achenes and sprouts from the Balti region of the Republic of Moldova.

Polyphenols Targeting MAPK Mediated Oxidative Stress and Inflammation in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic, systemic, autoimmune disorder, predominantly symmetric, which causes joint inflammation, cartilage degeneration and bone erosion, resulting in deformity and the loss of physical function. Although the management of RA has steadily improved, the pathophysiological mechanism is incompletely elucidated, and therapeutic options are still limited. Due to shortcomings in the efficacy or safety profiles of conventional RA therapies, therapeutic alternatives have been considered. Therefore, natural extracts containing polyphenolic compounds can become promising adjuvant agents for RA global management, due to their antioxidant, anti-inflammatory and apoptotic properties. Polyphenols can regulate intracellular signaling pathways in RA and can generate different immune responses through some key factors (i.e., MAPK, interleukins (ILs 1 and 6), tumor necrosis factor (TNF), nuclear factor light k chain promoter of activated receptor (NF-κB), and c-Jun N-terminal kinases (JNK)). The critical function of the Toll like-receptor (TLR)-dependent mitogen-activating protein kinase (MAPK) signaling pathway in mediating the pathogenic characteristics of RA has been briefly discussed. Oxidative stress can trigger a change in transcription factors, which leads to the different expression of some genes involved in the inflammatory process. This review aims to provide a comprehensive perspective on the efficacy of polyphenols in mitigating RA by inhibiting signaling pathways, suggesting future research perspectives in order to validate their use.

The Implication of Reactive Oxygen Species and Antioxidants in Knee Osteoarthritis

Knee osteoarthritis (KOA) is a chronic multifactorial pathology and a current and essential challenge for public health, with a negative impact on the geriatric patient's quality of life. The pathophysiology is not fully known; therefore, no specific treatment has been found to date. The increase in the number of newly diagnosed cases of KOA is worrying, and it is essential to reduce the risk factors and detect those with a protective role in this context. The destructive effects of free radicals consist of the acceleration of chondrosenescence and apoptosis. Among other risk factors, the influence of redox imbalance on the homeostasis of the osteoarticular system is highlighted. The evolution of KOA can be correlated with oxidative stress markers or antioxidant status. These factors reveal the importance of maintaining a redox balance for the joints and the whole body's health, emphasizing the importance of an individualized therapeutic approach based on antioxidant effects. This paper aims to present an updated picture of the implications of reactive oxygen species (ROS) in KOA from pathophysiological and biochemical perspectives, focusing on antioxidant systems that could establish the premises for appropriate treatment to restore the redox balance and improve the condition of patients with KOA.

An Up-to-Date Review on Citrus Flavonoids: Chemistry and Benefits in Health and Diseases

Flavonoids, the main class of polyphenols, are characterized by the presence of 2-phenyl-benzo-pyrane nucleus. They are found in rich quantities in citrus fruits. Citrus flavonoids are classified into flavanones, flavones, flavonols, polymethoxyflavones and anthocyanins (found only in blood oranges). Flavanones are the most abundant flavonoids in citrus fruits. In many situations, there are structure-function relationships. Due to their especial structures and presence of many hydroxyls, polymethoxies and glycoside moiety, the flavonoids have an array of multiple biological and pharmacological activities. This article provides an updated overview of the differences in chemical structures of the classes and members of citrus flavonoids and their benefits in health and diseases. The review article also sheds light on the mechanisms of actions of citrus flavonoids in the treatment of different diseases, including arthritis, diabetes mellitus, cancer and neurodegenerative disorders as well as liver, kidney and heart diseases. The accumulated and updated knowledge in this review may provide useful information and ideas in the discovery of new strategies for the use of citrus flavonoids in the protection, prevention and therapy of diseases.

Tunisian Olea europaea L. leaf extract suppresses Freund's complete adjuvant-induced rheumatoid arthritis and lipopolysaccharide-induced inflammatory responses

ETHNOPHARMACOLOGICAL RELEVANCE

Olea europaea L. (olive) is traditionally used as a folk remedy and functional food in Europe and Mediterranean countries to treat inflammatory diseases. O. europaea contains phenolic compounds and have been reported to prevent cartilage degradation. However, the function and mechanism of O. europaea in rheumatoid arthritis are not known.

AIM OF THE STUDY

In this study, we aimed to examine anti-inflammatory and anti-arthritic effects of Tunisian O. europaea L. leaf ethanol extract (Oe-EE).

MATERIALS AND METHODS

To do this, we employed an in vitro macrophage-like cell line and an in vivo Freund's complete adjuvant (AIA)-induced arthritis model. Levels of inflammatory genes and mediators were determined from in vivo samples.

RESULTS

The Oe-EE clearly reduced the production of the lipopolysaccharide-mediated inflammatory mediators, nitric oxide (NO) and prostaglandin E₂ (PGE₂), in RAW264.7 cells. The results of HPLC showed that Oe-EE contained many active compounds such as oleuropein and flavonoids. In AIA-treated rats, swelling of paws, pain, and cartilage degeneration were alleviated by oral Oe-EE administration. Correlating with in vitro data, PGE₂ production was significantly reduced in paw samples. Furthermore, the molecular mechanism of Oe-EE was dissected, and Oe-EE regulated the gene expression of interleukin (IL)-6, inducible NO synthase (iNOS), and MMPs and inflammatory signaling activation.

CONCLUSION

Consequently, Oe-EE possesses anti-inflammatory and anti-rheumatic effects and is a potential effective treatment for rheumatoid arthritis.

Emerging Natural-Product-Based Treatments for the Management of Osteoarthritis

Osteoarthritis (OA) is a complex degenerative disease in which joint homeostasis is disrupted, leading to synovial inflammation, cartilage degradation, subchondral bone remodeling, and resulting in pain and joint disability. Yet, the development of new treatment strategies to restore the equilibrium of the osteoarthritic joint remains a challenge. Numerous studies have revealed that dietary components and/or natural products have anti-inflammatory, antioxidant, anti-bone-resorption, and anabolic potential and have received much attention toward the development of new therapeutic strategies for OA treatment. In the present review, we provide an overview of current and emerging natural-product-based research treatments for OA management by drawing attention to experimental, pre-clinical, and clinical models. Herein, we review current and emerging natural-product-based research treatments for OA management.

A New Peracetylated Oleuropein Derivative Ameliorates Joint Inflammation and Destruction in a Murine Collagen-Induced Arthritis Model via Activation of the Nrf-2/Ho-1 Antioxidant Pathway and Suppression of MAPKs and NF-κB Activation

Oleuropein (OL), an olive tree secoiridoid and its peracetylated derivate (Per-OL) have exhibited several beneficial effects on LPS-stimulated macrophages and murine experimental systemic lupus erythematosus (SLE). This study was designed to evaluate dietary Per-OL in comparison with OL supplementation effects on collagen-induced arthritis (CIA) murine model. Three-weeks-old DBA-1/J male mice were fed from weaning with a standard commercial diet or experimental enriched-diets in 0.05 % (w/w) OL, 0.05% and 0.025% Per-OL. After six weeks of pre-treatment, arthritis was induced by bovine collagen type II by tail base injection (day 0) and on day 21, mice received a booster injection. Mice were sacrificed 42 days after the first immunization. Both Per-OL and OL diets significantly prevented histological damage and arthritic score development, although no statistically significant differences were observed between both compounds. Also, serum collagen oligomeric matrix protein (COMP), metalloprotease (MMP)-3 and pro-inflammatory cytokines levels were ameliorated in paws from secoiridoids fed animals. Mitogen-activated protein kinases (MAPK)s and nuclear transcription factor-kappa-B (NF-κB) activations were drastically down-regulated whereas nuclear factor E2-related factor 2 (Nrf2) and heme-oxygenase-1 (HO-1) protein expressions were up-regulated in those mice fed with OL and Per-OL diets. We conclude that both Per-OL and its parent compound, OL, supplements might provide a basis for developing a new dietary strategy for the prevention of rheumatoid arthritis.

Effects of oleuropein on tumor cell growth and bone remodelling: Potential clinical implications for the prevention and treatment of malignant bone diseases

Oleuropein (Ole) is the main bioactive phenolic compound present in olive leaves, fruits and olive oil. This molecule has been shown to exert beneficial effects on several human pathological conditions. In particular, recent preclinical and observational studies have provided evidence that Ole exhibits chemo-preventive effects on different types of human tumors. Studies undertaken to elucidate the specific mechanisms underlying these effects have shown that this molecule may thwart several key steps of malignant progression, including tumor cell proliferation, survival, angiogenesis, invasion and metastasis, by modulating the expression and activity of several growth factors, cytokines, adhesion molecules and enzymes involved in these processes. Interestingly, experimental observations have highlighted the fact that most of these signalling molecules also appear to be actively involved in the homing and growth of disseminating cancer cells in bones and, ultimately, in the development of metastatic bone diseases. These findings, and the experimental and clinical data reporting the preventive activity of Ole on various pathological conditions associated with a bone loss, are indicative of a potential therapeutic role of this molecule in the prevention and treatment of cancer-related bone diseases. This paper provides a current overview regarding the molecular mechanisms and the experimental findings underpinning a possible clinical role of Ole in the prevention and development of cancer-related bone diseases.

TLR4, RAGE, and p-JNK/JNK mediated inflammatory aggression in osteoathritic human chondrocytes are counteracted by redox-sensitive phenolic olive compounds: Comparison with ibuprofen

Osteoarthritic chondrocytes show an over-activity of inflammatory catabolic mediators, and olive products have attracted attention because they were discovered to have some benefits on osteoarthritis patients. We investigated the mechanisms of action of olive leaf polyphenolic compounds in osteoarthritic chondrocytes (OACs) using a standardized leaf extract, ZeyEX, and its main phenolic component, oleuropein, also compared with anti-inflammatory drug ibuprofen. OACs, isolated from joint-cartilages of Grade 4 OA patients, were found to express COMP and MMP-9 throughout their culture period. ZeyEX, oleuropein, and ibuprofen increased cell viability at concentrations of 1-100 nM, did not change at 500 nM-50 μM, but inhibited at ≥100 μM. The adherence profile of OACs increased with 1 μM of ibuprofen or ZeyEX and 10 nM-1 μM oleuropein. Although the markers for oxidative and nitrosative stresses (ROS and 3-NT) generally inhibited by three agents, the inhibitory effect of ZeyEX on 3-NT emerged dramatically (1 nM-10 μM). Lipid-hydroperoxides and HNE-adducts were also inhibited by each agent, but AGE-adducts unchanged by oleuropein while reduced by ZeyEX and ibuprofen. Inflammatory biomarkers, IL-1β, IL-6, Casp-1/ICE, and TNF-α, were inhibited by three agents, however osteopontin and GM-CSF by only ZeyEX and ibuprofen. A decreased COMP, TLR4, and RAGE expression levels were observed by three agents, but only the effects of ZeyEX was concentration-dependent. In particular, ZeyEX and oleuropein improved COL2, inhibited p-JNK/JNK, and increased GPx. COX2 was only inhibited by ibuprofen. The results indicate that polyphenolic-olive compounds counteract redox-sensitive inflammatory aggressions in osteoarthritic chondrocytes that may stop the progression of pathology and allow regeneration.

Oxidative stress and inflammation in osteoarthritis pathogenesis: Role of polyphenols

Osteoarthritis (OA) is the most prevalent joint degenerative disease leading to irreversible structural and functional changes in the joint and is a major cause of disability and reduced life expectancy in ageing population. Despite the high prevalence of OA, there is no disease modifying drug available for the management of OA. Oxidative stress, a result of an imbalance between the production of reactive oxygen species (ROS) and their clearance by antioxidant defense system, is high in OA cartilage and is a major cause of chronic inflammation. Inflammatory mediators, such as interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) are highly upregulated in OA joints and induce ROS production and expression of matrix degrading proteases leading to cartilage extracellular matrix degradation and joint dysfunction. ROS and inflammation are interdependent, each being the target of other and represent ideal target/s for the treatment of OA. Plant polyphenols possess potent antioxidant and anti-inflammatory properties and can inhibit ROS production and inflammation in chondrocytes, cartilage explants and in animal models of OA. The aim of this review is to discuss the chondroprotective effects of polyphenols and modulation of different molecular pathways associated with OA pathogenesis and limitations and future prospects of polyphenols in OA treatment.

Senolytic activity of small molecular polyphenols from olive restores chondrocyte redifferentiation and promotes a pro-regenerative environment in osteoarthritis

Articular cartilage and synovial tissue from patients with osteoarthritis (OA) show an overactivity of connexin43 (Cx43) and accumulation of senescent cells associated with disrupted tissue regeneration and disease progression. The aim of this study was to determine the effect of oleuropein on Cx43 and cellular senescence for tissue engineering and regenerative medicine strategies for OA treatment. Oleuropein regulates Cx43 promoter activity and enhances the propensity of hMSCs to differentiate into chondrocytes and bone cells, reducing adipogenesis. This small molecule reduce Cx43 levels and decrease Twist-1 activity in osteoarthritic chondrocytes (OACs), leading to redifferentiation, restoring the synthesis of cartilage ECM components (Col2A1 and proteoglycans), and reducing the inflammatory and catabolic factors mediated by NF-kB (IL-1ß, IL-6, COX-2 and MMP-3), in addition to lowering cellular senescence in OACs, synovial and bone cells. Our in vitro results demonstrate the use of olive-derived polyphenols, such as oleuropein, as potentially effective therapeutic agents to improve chondrogenesis of hMSCs, to induce chondrocyte re-differentiation in OACs and clearing out senescent cells in joint tissues in order to prevent or stop the progression of the disease.

Evaluation of the articular cartilage in the knees of rats with induced arthritis treated with curcumin

This study was designed to evaluate the anti-inflammatory effects of a curcumin treatment on the knee of rats with induced osteoarthritis. Fifteen adult rats were used and divided in three groups: the osteoarthritis group (OAG), control group (CG-without induction of osteoarthritis), and curcumin-treated osteoarthritis group (COAG). Osteoarthritis was induced in the right knee of rats in the OAG and COAG by administering an intra-articular injection of 1 mg of zymosan. Fourteen days after induction, 50 mg/kg curcumin was administered by gavage daily for 60 days to the COAG. After the treatment period, rats from all groups were euthanized. Medial femoral condyles were collected for light microscopy and immunohistochemical staining. The expression of SOX-5, IHH, MMP-8, MMP-13, and collagen 2 (Col2) was analyzed. The COAG exhibited an increase in the number of chondrocytes in the surface and middle layers compared with that of the OAG and CG, respectively. The COAG also showed a decrease in the thicknesses of the middle and deep layers compared with those of the OAG, and an increase in Col2 expression was observed in all articular layers (surface, middle, and deep) in the COAG compared with that in the OAG. SOX-5 expression was increased in the surface and deep layers of the COAG compared with those in the OAG and CG. Based on the results of this study, the curcumin treatment appeared to exert a protective effect on cartilage, as it did not result in an increase in cartilage thickness or in MMP-8 and MMP-13 expression but led to increased IHH, Col2, and SOX-5 expression and the number of chondrocytes.

Intra-articular injection of magnesium chloride attenuates osteoarthritis progression in rats

OBJECTIVE

To explore the effects of Mg²⁺ on the expression of osteoarthritic markers in human cartilage and synovium tissue explants. To investigate the therapeutic effect of intra-articular injection of Mg²⁺ in an established rat OA (Osteoarthritis) model of anterior cruciate ligament transection with partial medial meniscectomy (ACLT + PMM).

DESIGN

Human cartilage and synovium explants were collected from total knee replacement surgeries and incubated with MgCl₂ (20 mmol/L) in vitro. A rat OA model was established by ACLT + PMM surgery in 450-500 g male Sprague Dawley (SD) rats. To select the optimal dose, intra-articular injections of MgCl₂ (0.05, 0.5, 5 mol/L) were performed at 4 weeks after the surgery every 3 days for 2 weeks. The effect of optimized MgCl₂ was further determined by histology, immunohistochemistry, and quantitative real-time polymerase chain reaction.

RESULTS

The expressions of osteoarthritic markers in human cartilage and synovium explants were inhibited by Mg²⁺in vitro. Immunohistochemical analysis further suggested the inhibitory effects of Mg²⁺ on the expression of MMP-13 and IL-6 in the human tissue explants. Cartilage degeneration and synovitis in ACLT + PMM rats were significantly improved by intra-articular injections of Mg²⁺ (0.5 mol/L). Immunohistochemical analysis also showed the regulatory effects of Mg²⁺ on osteoarthritic markers in both cartilage and synovium in rats, consistent with in vitro results.

CONCLUSION

Intra-articular injections of Mg²⁺ at 0.5 mol/L attenuate the progression of OA in the ACLT + PMM rat model. Such effect was at least in part explained by the promotion of cartilage matrix synthesis and the suppression of synovial inflammation.

Dietary oleuropein and its new acyl-derivate attenuate murine lupus nephritis through HO-1/Nrf2 activation and suppressing JAK/STAT, NF-κB, MAPK and NLRP3 inflammasome signaling pathways

Systemic lupus erythemathosus (SLE) is a chronic inflammatory and autoimmune disease which can affect multiple organ systems, without an effective and safe treatment. Olive leaf extracts are of special interest for their therapeutic effects. Oleuropein (OL) is the most abundant constituents of olive leaf extract and possesses many beneficial properties. In this study, we evaluated the effects of dietary OL and its new derivate, peracetylated oleuropein (Per-OL), in a pristane-induced SLE model. Mice received an injection of pristane or saline solution and were fed with experimental diets: enriched with OL and Per-OL. The levels of proinflammatory cytokines and markers were evaluated by enzyme-linked immunosorbent assay. The protein expressions of inducible nitric oxide synthase, microsomal prostaglandin E synthase 1, heme oxygenase (HO-1), nuclear factor E2-related factor 2 (Nrf2), mitogen-activated protein kinases (MAPKs), Janus kinase/signal transducer and activator of transcription (JAK/STAT), nuclear transcription factor-kappa B (NF-κB) and inflammasome nucleotide-binding domain, leucine-rich repeats-containing family, pyrin domain-containing-3 (NLRP3) pathways activation were determined in kidneys by Western blot. OL and Per-OL significantly reduced renal damage and decreased serum matrix metalloproteinase 3 and prostaglandine E₂ kidneys levels. Our findings indicate that Nrf2 and HO-1 antioxidant protein expressions were up-regulated in mice fed with OL and Per-OL diets, whereas the activation of JAK/STAT, MAPK, NF-κB and NLRP3 inflammasome pathways was significantly ameliorated. These results suggest that OL and Per-OL supplementation might provide a new alternative approach as a preventive/palliative treatment of nephritis in SLE management.

Coll2-1 and Coll2-1NO2 as exemplars of collagen extracellular matrix turnover - biomarkers to facilitate the treatment of osteoarthritis?

Introduction: Osteoarthritis (OA) is the most common form of arthritis. However, there are no structure or disease-modifying OA drugs (DMOADs). Introducing personalized healthcare to patients and health-care practitioners is a high priority for the management of arthritic and musculoskeletal diseases. However, there are no biomarker tools that can be used for patient stratification, disease management, and drug development. Biomarkers are capable of diagnosing and prognosing some arthritic and musculoskeletal diseases. Cartilage-based biomarkers have the potential to be used in this context to guide the precision treatment of OA. Areas covered: The aim of this review is to focus on the pre-clinical and clinical utility of the Coll2-1 and Coll2-1NO2 biomarkers as unique cartilage-based biomarkers that can guide the development of new treatments for OA. This expert report will begin with a background to collagens and their important biomechanical roles in the musculoskeletal system, but particularly cartilage, before exploring the data and scientific evidence to support the utility of Coll2-1 and Coll2-1NO2 as unique biomarkers. Expert opinion: This review summarises the authors' expert view on the pre-clinical and clinical utility of the Coll2-1 and Coll2-1NO2 biomarkers and their potential for use as drug development tools.

CCL25-Supplemented Hyaluronic Acid Attenuates Cartilage Degeneration in a Guinea Pig Model of Knee Osteoarthritis

There is evidence that the application of mesenchymal stromal cells (MSCs) counteracts osteoarthritis (OA) progression. However, the prospect of extracting and expanding these cells might be limited. The aim of this study was to investigate whether hyaluronic acid (HA) supplemented with MSC-recruiting chemokine C-C motif ligand 25 (CCL25) can influence the natural course of spontaneous OA in the guinea pig. CCL25 concentration in synovial fluid (SF) was quantified with enzyme-linked immunosorbent assay. Boyden chamber cell migration assay was used to test CCL25-mediated migration of guinea pig MSC. Forty-nine 11-month-old male guinea pigs were divided into seven groups. The main treatments consisted of five intra-articular injections of HA in pure form and in combination with three doses of CCL25 (63, 693, and 6,993 pg) given at a weekly interval. The severity of cartilage damage was assessed by using a modified Mankin score. The measured average physiological concentration of CCL25 in SF of animals is 85 ± 39 pg/ml. MSC showed a 3.2-fold increase in cell migration at 1,000 nM CCL25 in vitro demonstrating the biological migratory activity of CCL25 on these cells. In vivo, treatment with HA alone did not reduce OA progression. Similarly, OA scores were not found significantly reduced after treatment with 63 pg CCL25 + HA. However, when compared to pure HA, treatment with 693 pg CCL25 + HA and 6,993 pg CCL25 + HA significantly reduced the OA score from 10.1 to 7.4 (-28%) and 8.4 (-20%), respectively. These data suggest that intra-articular injections of HA supplemented with CCL25 attenuates OA. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:1723-1729, 2019.

Chondroprotective Effects of Genistein against Osteoarthritis Induced Joint Inflammation

Genistein is an isoflavone extracted from soybean (Glycine max). This compound has anti-inflammatory, anti-oxidative, and anti-cancer effects; however, the mechanism underlying the effects of genistein on IL-1β-stimulated human osteoarthritis (OA) chondrocytes remains unknown. Our objectives in this study were to explore the anti-inflammatory effects of genistein on IL-1β-stimulated human OA chondrocytes and to investigate the potential mechanisms which underlie them. Our results from an in-vitro model of osteoarthritis indicate that genistein inhibits the IL-1β-induced expression of the catabolic factors nitric oxide synthase 2 (NOS2), cyclooxygenase 2 (COX-2), and matrix metalloproteinases (MMPs). Genistein was shown to stimulate Ho-1 expression, which has been associated with Nrf-2 pathway activation in human chondrocytes. In a rat model, genistein was also shown to attenuate the progression of traumatic osteoarthritis. Taken together, these results demonstrate the effectiveness of genistein in mediating the inflammation associated with joint disorders. Our results also indicate that genistein could potentially serve as an alternative therapeutic treatment for OA.

Curcumin Inhibits Proliferation of Synovial Cells by Downregulating Expression of Matrix Metalloproteinase-3 in Osteoarthritis

Objective

To investigate the association between curcumin and the differentially expressed genes (DEG) in synovial tissues of osteoarthritis.

Methods

Microarray analysis was used to screen for the DEG in osteoarthritis synovial cells. Curcumin‐related genes were identified through the drug–gene interaction network STITCH (http://stitch.embl.de/cgi/input.pl). Expression levels of fibronectin 1 (FN1) and collagen III protein were measured by western blot. MTT assay was used to examine the effects of different concentrations of curcumin on cell viability. Western blot and quantitative real‐time polymerase chain reaction were used to validate the different expression levels of matrix metalloproteinase‐3 (MMP3). Clone formation assay, flow cytometry, and the TUNEL method were conducted for detecting the cell proliferation and apoptosis rate.

Results

In the two chips of GSE1919 and GSE55235, the average expression of MMP3 in the osteoarthritis group was 63.7% and 12.9% higher than that of the healthy control, respectively. The results of western blot also showed that the average expression of MMP3 in 30 osteoarthritis patients was 132% higher than that of the healthy group, which confirmed that MMP3 was highly expressed in osteoarthritis group. The results of MTT showed that at 72 h, the cell viability of 40 μmol/L curcumin was the lowest and 79.6% lower than for the 0 μmol/L group, so the final curcumin concentration of 40 μmol/L was selected for subsequent experiments. Western blot results further showed that the expression of MMP3 was 44% lower in the untreated groups compared with the curcumin group, and the expressions of FN1 and collagen III were increased by 112% and 84%, respectively, which indicated that curcumin inhibited MMP3 expression and decreased osteoarthritis synovial cell activity. Cloning formation experiments showed that cell numbers increased by 75% and 20.5% in untreated and curcumin groups, and compared with the untreated group, the cells in the curcumin group decreased by 30.8%. Flow cytometry showed that the apoptotic rate in the curcumin group increased by 85.1% compared with the untreated group, but for a single group, MMP3 decreased the apoptotic rate by 53.9% and 46.7%, respectively.

Conclusions

MMP3 was highly expressed in osteoarthritis synovial cells. Curcumin could reduce cell viability, inhibit cell proliferation, increase cell apoptosis, and eventually alleviate inflammation of osteoarthritis by inhibiting the expression of MMP3.

Bone Health and Natural Products- An Insight

Bone metabolism involves a complex balance between matrix deposition, mineralization, and resorption. Numerous evidences have revealed that dietary components and phytoconstituents can influence these processes, through inhibition of bone resorption, thus exhibiting beneficial effects on the skeleton. Various traditional herbal formulae in ayurvedic and Chinese medicine have shown demonstrable benefits in pharmacological models of osteoporosis. The present review discusses normal bone metabolism and disorders caused by bone disruption, with particular reference to osteoporosis and current therapeutic treatment. Furthermore the effects of constituents from natural products on bone tissue are explained, with relevant evidences of efficacy in various experimental models.

Glycation marker glucosepane increases with the progression of osteoarthritis and correlates with morphological and functional changes of cartilage in vivo

Background

Changes of serum concentrations of glycated, oxidized, and nitrated amino acids and hydroxyproline and anticyclic citrullinated peptide antibody status combined by machine learning techniques in algorithms have recently been found to provide improved diagnosis and typing of early-stage arthritis of the knee, including osteoarthritis (OA), in patients. The association of glycated, oxidized, and nitrated amino acids released from the joint with development and progression of knee OA is unknown. We studied this in an OA animal model as well as interleukin-1β-activated human chondrocytes in vitro and translated key findings to patients with OA.

Methods

Sixty male 3-week-old Dunkin-Hartley guinea pigs were studied. Separate groups of 12 animals were killed at age 4, 12, 20, 28 and 36 weeks, and histological severity of knee OA was evaluated, and cartilage rheological properties were assessed. Human chondrocytes cultured in multilayers were treated for 10 days with interleukin-1β. Human patients with early and advanced OA and healthy controls were recruited, blood samples were collected, and serum or plasma was prepared. Serum, plasma, and culture medium were analyzed for glycated, oxidized, and nitrated amino acids.

Results

Severity of OA increased progressively in guinea pigs with age. Glycated, oxidized, and nitrated amino acids were increased markedly at week 36, with glucosepane and dityrosine increasing progressively from weeks 20 and 28, respectively. Glucosepane correlated positively with OA histological severity (r = 0.58, p < 0.0001) and instantaneous modulus (r = 0.52–0.56; p < 0.0001), oxidation free adducts correlated positively with OA severity (p < 0.0009–0.0062), and hydroxyproline correlated positively with cartilage thickness (p < 0.0003–0.003). Interleukin-1β increased the release of glycated and nitrated amino acids from chondrocytes in vitro. In clinical translation, plasma glucosepane was increased 38% in early-stage OA (p < 0.05) and sixfold in patients with advanced OA (p < 0.001) compared with healthy controls.

Conclusions

These studies further advance the prospective role of glycated, oxidized, and nitrated amino acids as serum biomarkers in diagnostic algorithms for early-stage detection of OA and other arthritic disease. Plasma glucosepane, reported here for the first time to our knowledge, may improve early-stage diagnosis and progression of clinical OA.

Electronic supplementary material

The online version of this article (10.1186/s13075-018-1636-6) contains supplementary material, which is available to authorized users.

The role of inhibition by phosphocitrate and its analogue in chondrocyte differentiation and subchondral bone advance in Hartley guinea pigs

Phosphocitrate (PC) and its analogue, PC-β ethyl ester, inhibit articular cartilage degeneration in Hartley guinea pigs. However, the underlying molecular mechanisms remain unclear. The present study aimed to investigate the hypothesis that PC exerted its disease-modifying effect on osteoarthritis (OA), in part, by inhibiting a molecular program similar to that in the endochondral pathway of ossification. The results demonstrated that severe proteoglycan loss occurred in the superficial and middle zones, as well as in the calcified zone of articular cartilage in the Hartley guinea pigs. Subchondral bone advance was greater in the control Hartley guinea pigs compared with PC- or PC analogue-treated guinea pigs. Resorption of cartilage bars or islands and vascular invasion in the growth plate were also greater in the control guinea pigs compared with the PC- or PC analogue-treated guinea pigs. The levels of matrix metalloproteinase-13 and type X collagen within the articular cartilage and growth plate were significantly increased in the control guinea pigs compared with PC-treated guinea pigs (P<0.05). These results indicated that articular chondrocytes in Hartley guinea pigs exhibited a hypertrophic phenotype and recapitulated a developmental molecular program similar to the endochondral pathway of ossification. Activation of this molecular program resulted in resorption of calcified articular cartilage and subchondral bone advance. This suggests that PC and PC analogues exerted their OA disease-modifying activity, in part, by inhibiting this molecular program.

Development and characterization of various osteoarthritis models for tissue engineering

Osteoarthritis (OA) is characterized by a progressive loss of articular cartilage, subchondral bone sclerosis and synovial inflammation and is the most common chronic condition worldwide today. However, most treatments have focused on pain relief and OA symptoms. For these reasons, many ongoing studies are currently trying to develop efficient and successful therapies based on its pathology. Animal models that mimic the histopathology and symptoms of OA have a critical role in OA research and make it possible to investigate both secondary osteoarthritic changes due to a precedent event such as traumatic injury and naturally occurring changes for the development of therapeutics which can be tested in preclinical and clinical OA trials. We induced OA in various animal models including rats, rabbits and guinea pigs by chemical, surgical and naturally occurring methods. In particular, the Dunkin-Hartley guinea pig is very attractive as an OA animal model because OA slowly progresses which is similar to human primary OA. Thus, this animal model mimics the pathophysiological process and environment of human primary OA. Besides the spontaneous OA model, anterior cruciate ligament transection (ACLT) with medial meniscectomy and bilateral ovariectomy (OVX) as well as a chemical technique using sodium monoiodoacetate (MIA) were used to induce OA. We found that ACLT in the rat model induced OA changes in the histology and micro-CT image compared to OVX. The osteoarthritic change significantly increased following ACLT surgery in the rabbit model. Furthermore, we identified that OA pathogenic changes occurred in a time-dependent manner in spontaneous Dunkin-Hartley guinea pigs. The MIA injection model is a rapid and minimally invasive method for inducing OA in animal models, whereas the spontaneous OA model has a slow and gradual progression of OA similar to human primary OA. We observed that histological OA change was extraordinarily increased at 9 ½ months in the spontaneous OA model, and thus, the grade was similar with that of the MIA model. Therefore, this study reports on OA pathology using various animal models as well as the spontaneous results naturally occurring in an OA animal model which had developed cartilage lesions and progressive osteoarthritic changes.

Cartilage regeneration and ageing: Targeting cellular plasticity in osteoarthritis

Ageing processes play a major contributing role for the development of Osteoarthritis (OA). This prototypic degenerative condition of ageing is the most common form of arthritis and is accompanied by a general decline, chronic pain and mobility deficits. The disease is primarily characterized by articular cartilage degradation, followed by subchondral bone thickening, osteophyte formation, synovial inflammation and joint degeneration. In the early stages, osteoarthritic chondrocytes undergo phenotypic changes that increase cell proliferation and cluster formation and enhance the production of matrix-remodelling enzymes. In fact, chondrocytes exhibit differentiation plasticity and undergo phenotypic changes during the healing process. Current studies are focusing on unravelling whether OA is a consequence of an abnormal wound healing response. Recent investigations suggest that alterations in different proteins, such as TGF-ß/BMPs, NF-Kß, Wnt, and Cx43, or SASP factors involved in signalling pathways in wound healing response, could be directly implicated in the initiation of OA. Several findings suggest that osteoarthritic chondrocytes remain in an immature state expressing stemness-associated cell surface markers. In fact, the efficacy of new disease-modifying OA drugs that promote chondrogenic differentiation in animal models indicates that this may be a drug-sensible state. In this review, we highlight the current knowledge regarding cellular plasticity in chondrocytes and OA. A better comprehension of the mechanisms involved in these processes may enable us to understand the molecular pathways that promote abnormal repair and cartilage degradation in OA. This understanding would be advantageous in identifying novel targets and designing therapies to promote effective cartilage repair and successful joint ageing by preventing functional limitations and disability.

Therapeutic Effects of Olive and Its Derivatives on Osteoarthritis: From Bench to Bedside

Osteoarthritis is a major cause of morbidity among the elderly worldwide. It is a disease characterized by localized inflammation of the joint and destruction of cartilage, leading to loss of function. Impaired chondrocyte repair mechanisms, due to inflammation, oxidative stress and autophagy, play important roles in the pathogenesis of osteoarthritis. Olive and its derivatives, which possess anti-inflammatory, antioxidant and autophagy-enhancing activities, are suitable candidates for therapeutic interventions for osteoarthritis. This review aimed to summarize the current evidence on the effects of olive and its derivatives, on osteoarthritis and chondrocytes. The literature on animal and human studies has demonstrated a beneficial effect of olive and its derivatives on the progression of osteoarthritis. In vitro studies have suggested that the augmentation of autophagy (though sirtuin-1) and suppression of inflammation by olive polyphenols could contribute to the chondroprotective effects of olive polyphenols. More research and well-planned clinical trials are required to justify the use of olive-based treatment in osteoarthritis.

Oleuropein down-regulated IL-1β-induced inflammation and oxidative stress in human synovial fibroblast cell line SW982

Rheumatoid arthritis (RA) is a chronic and systemic inflammatory autoimmune disease mainly characterized by aggressive hyperproliferation of synovial fibroblasts (SFs). It is accompained by a massive infiltration of inflammatory immune cells inducing progressive matrix degradation, destruction of cartilage and bone erosion through the production of inflammatory mediators. Oleuropein is the most prevalent phenolic component in olive leaves, seed, pulp and peel of unripe olives and is responsible for the characteristic bitter taste of unprocessed olives. This secoiridoid possesses well-documented pharmacological properties, including antioxidant and anti-inflammatory properties, and is available as a food supplement in Mediterranean countries. However, to date, anti-arthritic effects of oleuropein on SFs have not been yet elucidated. Thus, the aim of the present study was to investigate the potential effects of oleuropein, on IL-1β-induced production of inflammatory mediators and oxidative stress in the human synovial sarcoma cell line (SW982). In order to gain a better insight into mechanisms of action, signaling pathways were also explored. Cell viability was determined using the sulforhodamine B (SRB) assay. The expression of inflammatory cytokines IL-6, TNF-α, MMP-1 and MMP-3 was evaluated by ELISA. Moreover, changes in the protein expression of cyclooxygenase (COX)-2, microsomal prostaglandin E synthase-1 (mPGES-1) as well as mitogen-activated protein kinase (MAPKs), nuclear factor kappa B (NF-κB), and nuclear factor-erythroid 2-related and heme oxygenase-1 (HO-1) signalling pathways were analysed by western blot. Oleuropein exerted anti-inflammatory and anti-oxidant effects via down-regulation of MAPK and NF-κB signaling pathways and induction of Nrf2-linked HO-1 controlling the production of inflammatory mediators decreasing IL-6 and TNF-α cytokines, MMP-1 and MMP-3 levels and mPGES-1 and COX-2 overexpression. Thus, oleuropein might provide a basis for developing a new dietary strategy for the prevention and management of RA.

Review of Soluble Biomarkers of Osteoarthritis: Lessons From Animal Models

Objective Osteoarthritis (OA) is one of the leading causes of disability within the adult population. Currently, its diagnosis is mainly based on clinical examination and standard radiography. To date, there is no way to detect the disease at a molecular level, before the appearance of structural changes and symptoms. So an attractive alternative for monitoring OA is the measurement of biochemical markers in blood, urine, or synovial fluid, which could reflect metabolic changes in joint tissue and therefore disease onset and progression. Animal models are relevant to investigate the early stage of OA and metabolic changes occurring in joint tissues. The goal of this narrative review is to summarize the scientific data available in the literature on soluble biomarkers in animal models of OA. Design A literature search was conducted using the PubMed/Medline and Scopus databases between February 1995 and December 2015. All original articles, systematic and narrative reviews published in French or in English were considered. Results We summarized the data of 69 studies and proposed a classification scheme for OA biomarkers in animal studies, largely inspired by the BIPEDS classification. Conclusions Studies about biomarkers and animal models indicate that some markers could be valuable to monitor OA progression and assess therapeutic response in some animal models.

Insights into the Action Mechanisms of Traditional Chinese Medicine in Osteoarthritis

Osteoarthritis (OA) is a chronic degenerative joint disease characterized by articular cartilage destruction, synovial inflammation, and osteophyte formation. No effective treatments are available. The current pharmacological medications such as nonsteroidal anti-inflammatory drugs (NSAIDs) and analgesics, accompanied by possible adverse effects, might ameliorate OA symptoms. But they do not arrest the progression of OA. Traditional Chinese medicine (TCM) provides medical value by modification of disease and symptoms in OA. Valuable work on exploring TCM merits for OA patients has been investigated using modern technologies, although the complicated interacting network among the numerous components indicates the uncertainty of target specification. This review will provide an overview of the action mechanism of TCM in the last 5 years, discussing the TCM activities of anti-inflammation, antiapoptosis, antioxidation, anticatabolism, and proliferation in OA. TCM is a proposed medical option for OA treatment.

Experimental Modeling of Flavonoid-Biomembrane Interactions

Nonspecific interactions of flavonoids with lipids can alter the membrane's features (e.g., thickness and fluctuations) as well as influence their therapeutic potentials. However, relatively little is known about the details of how flavonoids interact with lipid components. Structure-dependent interactions of a variety of flavonoids with phospholipid monolayers on a mercury (Hg) film electrode were established by rapid cyclic voltammetry (RCV). The data revealed that flavonoids adopting a planar configuration altered the membrane properties more significantly than nonplanar flavonoids. Quercetin, rutin, and tiliroside were selected for follow-up experiments with Langmuir monolayers, Brewster angle microscopy (BAM), and small-angle X-ray scattering (SAXS). Relaxation phenomena in DOPC monolayers and visualization of the surface with BAM revealed a pronounced monolayer stabilization effect with both quercetin and tiliroside, whereas rutin disrupted the monolayer structure rendering the surface entirely smooth. SAXS showed a monotonous membrane thinning for all compounds studied associated with an increase in the mean fluctuations of the membrane. Rutin, quercetin, and tiliroside decreased the bilayer thickness of DOPC by ∼0.45, 0.8, and 1.1 Å at 6 mol %, respectively. In addition to the novelty of using lipid monolayers to systematically characterize the structure-activity relationship (SAR) of a variety of flavonoids, this is the first report investigating the effect of tiliroside with biomimetic membrane models. All the flavonoids studied are believed to be localized in the lipid/water interface region. Both this localization and the membrane perturbations have implications for their therapeutic activity.

The Pharmacological Potential of Rutin

The contemporary scientific community has presently recognized flavonoids to be a unique class of therapeutic molecules due to their diverse therapeutic properties. Of these, rutin, also known as vitamin P or rutoside, has been explored for a number of pharmacological effects. Tea leaves, apples, and many more possess rutin as one of the active constituents. Today, rutin has been observed for its nutraceutical effect. The present review highlights current information and health-promoting effects of rutin. Along with this, safety pharmacology issues and SAR of the same have also been discussed.

On the predictive utility of animal models of osteoarthritis

Animal models of osteoarthritis are extensively used for investigating disease pathways and for preclinical testing of novel therapies. Their predictive utility, however, has often been questioned, mainly because preclinical efficacy of novel therapeutics is poorly translated in clinical trials. In the current narrative review, we consider the preclinical models that were used to support undertaking clinical trials for disease-modifying osteoarthritis drugs, and compare outcomes between clinical and preclinical studies. We discuss this in light of the 1999 Food and Drug Administration draft guidelines for industry for use in the development of drugs, devices, and biological products intended for the treatment of osteoarthritis, which raised five considerations on the usefulness of osteoarthritis models. We systematically discuss what has been learnt regarding these five points since 1999, with emphasis on replicating distinct risk factors and subtypes of human osteoarthritis, and on comprehensive evaluation of the disease in animals, including pathology of all joint tissues, biomarker analysis, and assessment of pain and joint function. Finally, we discuss lessons learnt and propose some recommendations for how the evidence from preclinical research might be strengthened with a view to improving success in clinical translation.